While my front end was all stock, back 60K miles ago, I had to hold my steering wheel about that much or a bit more to the left to keep me running straight, most of the time (highway and around town). I didn't mind that much. A bunch of mods later, including the 09 steering linkages, steering brace, bigger tires, suspension, yada yada yada...my steering was way better then before but still kind of had some slop but not enough that it made me feel unsafe. Figured because of the bigger tires I was still going to get some slop in the steering wheel. I bought the high mount Bilstein Steering Stabilizer as just another upgrade. Believe it or not my steering became a lot tighter. Not perfect, but so much better!
I've asked a bunch of mechanics, that I trust, before I installed the Bilstein Steering Stabilizer about adjusting the steering box. Universal answer I got is "you can but I don't recommend it." I've also thrown around the idea of replacing the steering linkage to the steering box. I try to practice what I preach "if its not broken, don't fix it." Doesn't work all the time and for everything, but its saved me a few headaches over the years. So far mine is working fine. (Knock on wood).
As for the wobbling on the highway, the last time I experienced that was when I owned an old 91 Ford F-150 with the 5.0 in it when I was 17. Don't judge, I didn't know better and couldn't afford the truck I have now haha. Just about every joint you can think of was bad on that Fords front end, so bad that I barely drove it on the highway it wobbled so much. And when I did I was white knuckling it. But I made a killing for a 17 year old plowing and hauling things around town with that truck. SO glad I got rid of it!
That's just been my personal experience with my trucks wobbling and wandering. Someone else may have more knowledge. I'd suggest going through the motions of having all the joints, alignment, etc checked out. It wont hurt. I still have a bit of slop in my steering on my 07, like I said its not perfect. Its a big diesel truck, not a tin can prius, and that's what I love about it! Good Luck!